package Ali;

import java.util.Scanner;

public class Main_0915_1 {
    public static void main(String[] args) {
        Scanner cin=new Scanner(System.in);
        double x=cin.nextInt();
        StringBuffer sb=new StringBuffer();
        while (x>0){
            //找到x最大可以换到哪个字符
            int n=0;
            double maxCount=1;
            while (maxCount<x&&n<26){
                n++;
                maxCount=Math.pow(2,n);
            }
            char c= (char) ('a'+n-1);
            if (n==0){
                c='a';
            }
            sb.append(c);
            if (n==0){
                x--;
            }else {
                x=x-Math.pow(2,n-1);
            }
        }
        System.out.println(sb.toString());
    }
}
